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Hi all,

Robert (PA2RDK) has sent to me great photos and modification of my program. That's what Robert wrote to me:

 

Hi Jure,
 
This weekend I'm playing with your weekend project. I like it very much, it's a very nice concept and a beautiful print.
 
 
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Hi all,

my friend Marko, who is also building his DRA818 VHF/UHF Radio audio transceiver has published an Arduino code. Marko has also made a very nice outline on Nokia 5510 LCD. See the image below.

Read more if interested...

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Hi,

 

just to let you know my Weekend VHF/UHF radio will be displayed - thanks to ZRS, on the HAMRADIO fair in Friedrichshafen on the booth of ZRS - Slovenian HAM radio organization:

Zveza Radioamaterjev

Slovenije (ZRS)

hall/stand no.:  A1-247

 

If you happen to visit this fair please come around and say hi to my colleagues who will be on the booth.

73 de Jurij, S52CQ 

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Hi,

so finaly things are getting forward. I have got Nokia5510 LCD and modified the SW so that I can show much more information on the LCD. Since transceiver is dual band it's sensible to have dual band display. See attached photo:

VHF UHF2

 

Read more if interested...

 

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Hi,

 

it has been happening a lot over here. I have already wrote that the VHF module can receive also on UHF. Therefore I have used Nokia 5510 LCD to display frequency for both bands: 144 MH and 433 MHz.20150505 215220

 

Read more if interested.

 

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Hi,

 

here is another update. I am impressed with DRA818 modules, although I have noted that scanning command does not work. Also some other functions that similar modules offer, do not work, like microphone level, scrambling, sensing SMS messages. If interested read on...

I got many feedback to my posts, some were concerning PCB which is partly SMD partly THT. Apparently some users have problems with soldering SMD components so I have designed a PCB with "classical" THT components. See image below. The PCB can be purchased here.

 

With respect to the program, I have tested 1.5" OLED as display and it does perform nicely, but somehow numbers/letters on it are rather small. So I have tested also Nokia5510 GLCD (82x82pixel) and this one was much better. The program that I am currently working on supports receiving on two bands (VHF&UHF), because DRA818V modules can receive also UHF signals. Unfortunately they do not transmitt well on UHF.

One of the future projects with these modules will be a Micro repeater. It will contain one VHF and one UHF module, duplexer, LiPo, sollar cell and some logics. It should be a self contained micro repeater for local work. Will post more info in the blog as the project evolves.

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Hi all,

 

here is the follow up of this project. Schematic diagram is attached, the Bascom SW can be found on this link in the Download section of my web page.

 

Click to image to get full PDF schematics.

On the schematics I need to add some explanations.IC5 is basically not needed if the board is about to be powered from 12V. IC5 was added in case that the board was powered directly from LiPo cell (nice feature for Portable work where we need every Watthour from the battery). Fully powered LiPo can have 4.5V, while it's normal voltage is below 4V, which may cause that LCD might not  have propper contrast, hence we need IC5 to add that much negative voltage so that LCD displays in order. If you ommit IC5 then the middle contact of J2 should be connected directly to GND.

On the board you will find also microphone preamplifier. This was added after during tests electret mike did not perform well enough. You may want to adjust amplification of the preamp around Q2 and change R10 - smaller R10 means smaller amplification. On this schematics a dynamic microphone was used.

Perhaps you'd want firstly to try your electret mike without Q2. In this case you do not need to use R10, C23 (and Q2) and connect electret mike to junction R1/C3.

Jumper J1 was meant to achieve higher amplification of the LM386. During testing I have seen that LM386 has enough amplification with J1 open, but you may want to try that yourself.

SP2 is active buzzer, which sounds when we confirm settings done with encoder.

The Bascom program cannot be described in few lines, but it's also rather well commented so there should be no problem when you want to modify it. This version of the programme is for 134 to 174 MHz band, while I am already preparing 400 to 470 MHz version.

Best regards

Jurij

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Hi all, 

not long ago I have seen DRA818V module, which is a complete FM HAM radio station that requires microphone, AF amplifier and a MCU. So I have ordered a couple of them and by the time I got modules, I have designed a PCB. And it turned out that this was really a weekend project, PCB was soldered in no time, in the rest of the weekend I wrote first version of Bascom-AVR program and after some HW problems the radio station was nicely working by the Sunday evening. Read more if interested.

 

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Hi all,

I have done a USB HM-TRP adapter as seen on the photo below. USB HM-TRP adapter works on 868 MHz ISM band (Europe) or 915 (Australia, USA). It is a great tool because with it's UHF embedded module it can have a range of over 2 km in the open.

 

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Hi all,

I am announcing a new interesting accessory for all AVR programmers. It's upgraded AVR fuse programmer that's being described in the book on the page 147 (click the link).

We have upgraded fuse programmer so that now it's a stand alone programmer.

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